1. Field of the Description
The present invention relates, in general, to anti-counterfeiting devices for currency and brand authentication, and, more particularly, to currency and brand authentication elements, and methods of designing and manufacturing such authentication elements, that are configured to provide a multi-planar image that is viewable without special eyewear and that is difficult, if not nearly impossible, to replicate or copy.
2. Relevant Background
Anti-counterfeiting efforts often involve use of an anti-counterfeiting device or element that is made up of an array of lenses and an image printed onto the back of the lens array or onto an underlying substrate or surface (e.g., a sheet of paper or plastic). The anti-counterfeiting element may be used to display an image that is chosen to be unique and be an indicator that the item carrying the anti-counterfeiting element is not a counterfeit. The anti-counterfeiting market is rapidly growing worldwide with anti-counterfeiting elements placed on a wide range of items such as upon currency (e.g., on a surface of a paper bill to help prevent copying) and on labels for retail products (e.g., labels on clothing showing authenticity).
In this regard, moiré patterns have been used for years in anti-counterfeiting elements with arrays of round lenses and with arrays of hexagonal lenses (or round and hexagonal lens arrays). Typically, the printed images provided in an ink layer under these lens arrays are small, fine images relative to the size of the lenses. A moiré pattern is provided in the printed images in the form of a secondary and visually evident superimposed pattern that is created when two identical patterns on a surface are overlaid while being displaced or rotated a small amount from each other.
In such moiré pattern-based anti-counterfeiting elements, some of the images may be printed in a frequency slightly more or less frequent than the one-to-one dimension of the lenses in two axes, and some of the images may be printed slightly differently relative to each other. While helpful to reduce counterfeiting, use of moiré patterns with round lens arrays has not been wholly satisfactory for the anti-counterfeiting market. One reason is that the effects that can be achieved with moiré patterns are limited, and the effect is often relatively easy to reverse engineer, which limits its usefulness as an anti-counterfeiting element. For example, printing the underlying image is becoming easier to accomplish due to high resolution lasers and setters and other printing advances. Typically, for an element, the micro-lenses are printed using an emboss and fill technology, which limits the printing to one color due to the fact that the process tends to be self-contaminating after one color and also due to the fact that the process is difficult to control from a relative color-to-color pitch in the emboss-and-fill printing process.
In other cases, holograms and lens features are used for security devices in currency, brand authentication, and brand protection as well as on high security documents. Holograms are becoming increasingly less secure, in part, due to the rise in technology, programming, and general availability of programs that allow one to easily create holograms. In many applications, the cheaper dot matrix holograms are “good enough” to simulate many of the effects of the more expensive elaborate holograms used in anti-counterfeiting elements. While lens features done properly can be more secure than hologram elements, there is a need for a new technology to combat the currency and product counterfeiting. Ideally, the new technology would have attributes that are not possible with holography or micro lenses.
Hence, there remains a need for advancements in the design and fabrication of assemblies or elements that display imagery useful for anti-counterfeiting and/or product/document authentication. For example, such improvements may allow new anti-counterfeiting devices or elements to be produced for use with currency, labels, credit/debit cards, and other items, and these anti-counterfeiting devices preferably would be much more difficult if not nearly impossible to duplicate or copy. Further, there is a growing demand for such anti-counterfeiting devices to provide a surprising visual effect or “wow factor” with their displayed imagery such as images that float above and/or below a focal plane (e.g., more true 3D displays) rather than merely laterally reflecting back light such as with a sequence of mirrors or mirrored surfaces or using reproducible holograms.